Are there any mundane items that deal with sickened condition?
No, there are no mundane items that remove the Sickened condition.
You might expect there to be "medicinal herbs" or something that would do this, but as far as I can tell with some searching, nothing like that exists in the rules.
If you're willing to step outside the realm of "mundane items," you have a few options, but most of them require at least some amount of investment of character resources, not just a handful of gold pieces:
- Being naturally immune: Warforged are naturally immune to the sickened condition.
- Strong Stomach (feat, Dungeonscape p. 64): This feat, which requires Con 13 and Endurance, makes you immune to the sickened condition.
- The Panacea spell (SpC p. 152): Cleric 4/Druid 5 spell that removes a variety of conditions, including Sickened.
- The Healing Lorecall spell (SpC p. 110): Cleric 2/Druid 2/Ranger 1 spell that allows the caster to remove conditions, including Sickened, with subsequent curing spells, as long as they have enough ranks in the Heal skill.
- The Resurgence spell (SpC p. 174): Cleric 1/Paladin 1/Blackguard 1 spell that grants a new saving throw to someone to avoid an effect they're already suffering. This can remove Sickened if the original effect allowed a saving throw (which many do).
- The Heal spell: Removes a whole lot of things, including Sickened. Very high level, though.
The spell options from the above list, of course, can be made into wands, so if you or a party member have the relevant spell(s) on your class list, or a few ranks in Use Magic Device, that's a way to get access to them without much of an investment of character resources, just a bit of gold. A wand of Resurgence, in particular, is a great thing for someone in the party to have.
Finally, let me suggest my personal favorite method of dealing with the Sickened condition, which requires zero investment of gold or character resources: ignoring it completely.
At the end of the day, all that Sickened actually does is give you -2 on a few checks. This does include saving throws, which is pretty bad, so you'd definitely rather have it not happen to you, but it's not like Nauseated, Staggered, or Panicked, where it actually prevents you from taking actions. Usually, even if you do have the ability to do so, it's not worth spending an action to remove the Sickened condition. The best way to deal with being Sickened is often to let out a big sigh, and then take the same action you were going to take anyway, but with a -2 penalty.